How To Install GTS Quarter Panels - Wider Is Better

Installing GTS Widened Rear Quarter-Panels On A '64

The fender change on this '60 Corvette is subtle once painted, but the ability to run larger tires is significant.

One of the biggest problems with going the resto-rod route on a C1 or C2 Corvette is the lack of space in the rear wheelwells. What good is it to install a fire-breathing engine under the hood if the only tires you can install in the rear are too skinny to grab the pavement when you mash the throttle? Thanks to Greg Thurmond, owner of GTS Customs in Simi Valley, California, there's now a sanitary way to modify your vintage Corvette so you can stuff 9.5-inch wheels wearing P275-style rubber under the rear quarter-panels without having the car look like a '70s-era Trans-Am Racer.

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The new GTS widened rear quarter-panels for all '56-'60 C1 and '63-'67 C2 Corvettes are the perfect fix. They fit into the stock rear quarter-panel placement just like the stock skinny fenders. Widened rear quarters for '61-'62 Corvettes will be available eventually. The C1 panels provide about 1.5-inch additional clearance in the rear, and the C2 units add about 1 inch of room per side. Best of all, the panels not only allow the use of more reasonable wheel and tire sizes, but the widening is subtle and generally goes unnoticed by anyone save the most seasoned NCRS judge.

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New, wider, rear fender panels are available for C1 and C2 Corvettes.

If you're comfortable ripping pieces off your vintage car and doing fiberglass work, this could be a DIY project. However, you may want to consider having a professional do the work, since any mistakes made at this stage will greatly affect the quality of the paint applied later. In addition, owners often opt to build wider bumpers to follow the new, wider contours of the body.

Follow along with Thurmond and John Holloway as they apply the full fender upgrade to a '64 Corvette.

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The fender change on this '60 Corvette is subtle once painted, but the ability to run larger tires is significant.

New, wider, rear fender panels are available for C1 and C2 Corvettes.

The GTS quarter-panels come with a line denoting the point at which they should be cut to fit the original body line. This is a carryover from the original plan, which was to have the new quarter mate with the body at the peak over the fender. Later molds omit this material. Thurmond trimmed it with a saber saw and a 10-tooth-per-inch blade designed for wood. Note the dust mask and safety glasses-these are a must for this kind of work.

This quarter-panel was missing a vertical bonding strip that should be located in the wheelwell just aft of the wheel. Thurmond said this could be indicative of a previous accident and panel replacement. The strip will be replaced later.

The adhesive and fiberglass residue on the original bonding strip where the old panel was attached had to be cleaned away. A 40-grit wheel on an air grinder quickly smoothed down the area to bare fiberglass. Note the "flange" revealed by the grinding-that's the factory bonding strip.

After giving the old quarter-panel a few authoritative whacks with a hammer along the bonding lines to weaken them, Thurmond used a hammer, chisel, and old screwdrivers to break the bond between the original panel and the rest of the body.

Thurmond used the old panel to rough out the cuts on the new one. Surgical precision isn't required at this step since there will be more fitting and trimming when the panel is mated to the car. Remember, it's always best to be conservative with your cuts.

The surfaces where the bonding solution will be applied to the new quarter-panel were worked over with a 40-grit wheel to give the adhesive some bite. The bonding strips on the car were given similar treatment.

Thurmond and Holloway dry-fit the panel to the car several times, making note of areas that required additional trimming or grinding.

Once the fit was perfect, the panel was attached using several wood screws. It was important at this stage to drill and install only one screw at a time while finalizing the fit of the panel. These screws were used to hold the panel in place while the adhesive set up.

The new panel was ready to be bonded to the car. GTS used Mar-Glass, an auto body filler and adhesive, which was applied to the bonding strips after it was mixed with hardener.

The panel was screwed and clamped back into place. GTS used spatulas to apply Mar-Glass to fill voids and smooth the adhesive. It's left to set up for 24 hours before grinding.

With the Mar-Glass completely dry, the screws were removed. Holloway got busy with a 40-grit disk on a DA sander, removing the excess adhesive and feathering away the hard edge in the channel. If this wasn't done, the line would eventually become visible under the paint.

The screw holes were touched up with a die-grinder. The aim was to feather the holes and leave a slight depression for fiberglass patches. After the holes were dusted and wiped clean, Holloway cut small, circular patches from the fiberglass cloth slightly larger than the size of the feathered area.

Thurmond got busy with the fiberglass on the body seams. He used two long strips of cloth, each enough to cover the seam from the door jamb and over the peak on the decklid. The area along the seam was given a liberal coat of resin; the cloth was applied, then worked in with the paintbrush until it was saturated.

The work continued on the rear fascia, using two layers of shorter pieces of the cloth. Retain as much of the sharp edges on the body's fillets and rounds as possible. Make sure the 'glass cloth is well saturated.

Holloway mixed up and applied a skim coat of Mar-Glass filler/adhesive, making sure to apply enough pressure for the material to fill. After about 30 minutes of curing time, he sanded away most of this with an 80-grit block. He used a wire brush to clean the paper when it loaded up with the still-soft material, then hit it with 80-grit paper, and again with 150-grit on a pad.

This is what it looks like after using the 150-grit sanding block. The panel was ready for primer, more sanding, and preparation for paint in the usual way. GTS recommends applying primer, hitting it with an 80-grit block, priming it again, going over it with a 200-grit block, spraying a guidecoat, then sanding with a 400-grit pad.

With our LS3 Small-Block Build, we upgrade it with a cam and heads, then put the same stuff on a 418-inch stroker. Click here for more details or check out the July 2012 issue of Super Chevy Magazine » Read More